How to send input in a new terminal using Shell Script

Question

I found out how to automatically send input to a C program using Shell Script. For example, if I compile this C program:

//test.c int main() } int x; printf("Please enter an integer:"); scanf("%d", &x); printf("\nYou entered %d\n", x); } 

and write this script:

#!/bin/bash ./test << EOF 5 EOF 

and open the terminal and run the script I will get this output:

Please enter an integer: You entered 5 

Now, I want test to run on a new terminal, which I found out that I can do with this command:
gnome-terminal -x ./test
The problem is, if I try to do both at the same time in my script (run test on a new terminal AND automatically send input), it doesn't work, the input doesn't get sent on the new terminal, you just have to give it yourself like you normally would.

What am I doing wrong and how to fix this?

P.S. Sorry if the format is a bit messed up, I tried.

Answer 1

It will work if you use your shell script rather than the binary.

$ ~/tmp/term_test$ cat ./test_wrapper.sh #!/bin/bash ./test << EOF 5 EOF read dummy $ gnome-terminal -x ./test_wrapper.sh $ 

The "read dummy" line I added will stop the terminal from immediately closing when the script completes.

Are you sure that you need to open a new terminal session?

Answer 2

I think I have found a way to achieve what you want, but I think you will want to learn about redirection to avoid the rather messy output.

I used job control (& - run in background) to be able to run 2 instances simultaneously. See the bash man page for more details. You will also find coverage of redirection there.

I added a sleep to you C example simply so that it doesn't terminate immediately. michael@bunchan:~/tmp/term_test$ echo 5 | ./test Please enter an integer: You entered 5 michael@bunchan:~/tmp/term_test$ echo 99999 | ./test Please enter an integer: You entered 99999 michael@bunchan:~/tmp/term_test$

michael@bunchan:~/tmp/term_test$ $ cat test.c //test.c #include <stdio.h> #include <unistd.h> int main() { int x; sleep(10); printf("Please enter an integer:"); scanf("%d", &x); printf("\nYou entered %d\n", x); } $ ./test & << EOF > 999 > EOF [1] 10638 $ ./test & << EOF 5 EOF [2] 10639 $ jobsPlease enter an integer: [1]+ Stopped ./test [2]- Running ./test & $ Please enter an integer:jobs [1]- Stopped ./test [2]+ Stopped ./test $ 

Answer 3

Here is a better answer to your original question, use a pipe rather than a redirection.

$ echo 5 | ./test Please enter an integer: You entered 5 $ echo 99999 | ./test Please enter an integer: You entered 99999 $